The present invention relates to under-dash pedal systems for vehicle control, and more particularly relates to adjustable foot pedals that are adjustable relative to a seated person in a vehicle for optimal positioning and function.
Adjustable foot pedal systems for control of vehicles are known. For example, see U.S. Pat. No. 3,828,625. However, improvements are desired to allow linear adjustment of the pedals so that a location of the pedals to the vehicle floor and to the driver can be more appropriately controlled. For example, it is desirable to adjust the pedals in a manner that is most similar to adjusting a vehicle seat, since linearly adjusting a vehicle seat relative to foot pedals is widely accepted by the public and government regulators. However, a problem may result if the pedals are linearly adjusted, because with conventional thinking, this requires that the actuators (e.g. push rods, cables, and mechanical linkages) connecting the pedals to the associated vehicle components (e.g. a master brake cylinder, an engine throttle, or a clutch) be lengthened or shortened as the pedals are adjusted. Some designers are hesitant to make a length of actuators adjustable because this can introduce play, wear, and reduced reliability into the actuator. Nonetheless, there are potential cost savings if foot pedals are made adjustable instead of a vehicle seat being adjustable on a floor pan of the vehicle.
Even if the above challenges are overcome, the adjustable pedal system must be able to meet certain functional criteria. For example, the braking pedal must be able to withstand significant loads and torsional stress that occurs during hard braking of the vehicle. Further, the accelerator and brake pedal systems should preferably position the accelerator pedal and the brake pedal at the same relative positions after an adjustment, so that the driver does not mis-hit or have other problems when quickly switching from one pedal to the other. At the same time, the accelerator and brake pedal systems must be relatively simple, reliable, and very durable for long use. Another problem is caused by horizontally/rearwardly extending and protruding objects. It is undesirable to incorporate such protruding objects under an instrument panel or dash, especially in a relatively low position, where they can cause leg and knee injury during a vehicle crash. Also, there is not much room under an instrument panel, such that any pedal system must take up a minimum of space.
It is noted that vehicle brake pedals undergo a high number of low-stress cycles of use during normal braking, and further periodically undergo a significant number of high stress incidents, such as during emergency braking. Historically, loose joints and wear were not a problem, since stiff brake pedal levers were simply pivoted to a durable vehicle-attached bracket by a high-strength lubricious pivot pin. However, adjustable pedal systems have introduced additional joints and points of potential durability problems, as discussed below.
It is further noted that one reason that many vehicle manufacturers are now considering adjustable foot pedals is because there are advantages of improved air bag safety and lower cost to adjusting the location of pedals instead of moving a steering column, vehicle seat, and/or occupant. However, this has introduced joints and components into the brake pedal system that were not previously present. For example, in an adjustable pedal system where a linear adjustment device is introduced between the pedal lever and the pedal pivot, the adjustment device must be made of a first track component attached to the pedal lever and a second track component attached to the pedal pivot, all of which must be attached and adjustably interconnected in a manner that does not become loose over time under either low-cycle high stress or high-cycle intermediate stress. Further, all components in the system must provide consistently high bending or torsional strength, despite dimensional and other manufacturing variations. At the same time, the joints must preferably be simple, low cost, reliable, effective, robust, and readily manufacturable.
One more subtle problem with existing adjustable pedals which are designed for linear travel is that while they are able to effectively withstand the forces applied directly for and aft when applying the brake, they are often relatively weak when a load or force is applied in a cross-car (side-to-side) direction. The pedals typically have excess and undesirable lash or looseness in the side-to-side direction and are subject to failure under relatively low loads. Further, they are subject to customer complaint and/or poor “feel” during use.
Additionally, due to the inability of current linear adjustment mechanisms to withstand lateral loading and high torsional loads, the pedal beams and pads must be located just under the adjustment mechanism with little offset side-to-side, so that minimal torque is applied to the adjustment mechanism. In today's vehicle designs, and in particular with smaller vehicles, there are often many obstructions under the vehicle dash, such as the steering column, and limited room for location of the adjustment mechanism. Therefore, there is often a need for the pedal beam and pad to be offset from the adjustment mechanism to fit into limited available space. This offset may put a large torsional load on the adjustment mechanism, which must have the ability to resist the load without chance of failure and without lash or looseness in the system. Additionally, to keep the loads and stresses to a minimum on the pedal adjustment mechanism, it is desirable in current linear adjustment systems to locate the adjustment mechanism as low as possible in the vehicle to reduce the moment arm and stress induced in the adjustment mechanism. This further places limitations on the flexibility of the system to package or fit in tight vehicle spaces under the dash.
The present inventive system is designed to overcome the problems described above and which are experienced with existing adjustable pedal systems. Because of the unique channel design, it is able to resist very large lateral and torsional loads. The benefit of this is that the present inventive system has very little looseness or lash. It can easily withstand large fore-aft and lateral loads with little deflection, looseness, or failure. Additionally, the pedal can be offset by as much as 70 mm in a side-to-side direction, which gives the vehicle designers great flexibility in designing a pedal system around the many obstructions in a vehicle, especially smaller vehicles. Another benefit of the present inventive system, is that the adjustment mechanism can be located relatively high in the pedal support bracket as the system is able to withstand the high loading resulting from a long pedal beam or from the large torsional loading condition. This provides great flexibility for packaging in the vehicle.
One problem typical with many adjustable pedal systems, is that the loads or forces applied to the pedals, are transferred through and resisted by the adjustment mechanism drive gears. Ideally, the adjustment mechanism gears would be designed for the sole purpose of moving the pedal in the fore-aft positions and would not take a lot of load from the application of the pedal. They could then be designed small and very economically. But when the adjustment mechanism gears must also be designed to resist the forces applied on the pedal, they must be designed large and strong enough to withstand tremendous loads that are applied to the pedal. This will add cost and complexity to the gears and will create a condition where they are subject to failure or unnecessary wear.
There are at least two types of pedal systems. One is a pivoting system which adjusts the fore-aft position of the pedal by rotation of the pedal around a pivot in the pedal support bracket. Because of the relatively short radius of the arc or radius of travel (typically 225-325 mm), the pedal will change its height relative to the floor by as much as 20 mm when traveling a fore-aft distance of 75 mm as the pedal moves about the arc. Additionally, the angle of the pedal can change as much as 12-15 degrees. Although this type of system may be relatively small and easy to package in a vehicle environment, the large change in height of the pedal relative to the floor, and the large change in angle of the pedal pad, may cause confusion of the driver or undesirable positioning of the foot on the pedal.
Another type of system adjusts the pedal linearly. An adjustable pedal system, which adjusts the pedal position in a linear fashion, can move in the fore-aft direction a distance of 75 mm with no change in height relative of the pedal to the floor, if desired. This is clearly an advantage to the designers of a vehicle as the pedal travel can be designed for optimum comfort and ergonomics of the driver. Unfortunately, these systems require a large adjustment mechanism, which is often difficult to fit or package in many vehicles. Further, such systems include components elongated in a rearward horizontal direction toward a vehicle drive, which can be undesirable.
The inventive adjustable pedal systems described below include a track and follower, and further include polymeric bearing shoes therebetween to provide a smooth sliding motion. Because of the high torsional stresses on these pedals, particularly on brake pedals, it is difficult to design a low cost solid bearing that is sufficiently tight to not be sloppy, yet that is able to be assembled easily. Further, the bearing shoe should not wear and become sloppy over time, even under high stress and/or high cycle use. Further, it is desirable that the present bearing provide a consistent low level of friction to help keep the pedal in an adjusted position, so that other components do not absorb all of this stress.
Accordingly, an apparatus solving the aforementioned problems and having the aforementioned advantages is desired.